From Billy Butlin to Lakshmi Mittal, top tycoons have always called this place home. Arab princes throw wild parties in marble-pillared mansions here; up the road, Asil Nadir and Emil Savundra plotted multi-million-pound frauds; and a few doors away fashion boss Aristos Constantinou was shot to death.

As long as you're rich enough, nobody really minds what you get up to here - although residents did start a petition to keep Boy George out.

Welcome to The Bishops Avenue in East Finchley - probably the richest little street in the world.

For decades, locals called it Millionaire's Row. Inflation alone means Billionaire's Row is a better description today. But high oil prices and a recent spate of building and redevelopment up and down the street mean only one thing: this tree-lined kilometre of north London is once again the undisputed destination of choice for some of the world's largest - and most precarious - fortunes.

'The street is extraordinary, a phenomenon of modern times,' says Trevor Abrahamson, the area's leading estate agent. 'Among the wealthiest circles in the world, The Bishop's Avenue is better known than Buckingham Palace. This country is known to be the place to go to protect yourself against uprisings or inflation. Every time there is political instability or a surge in energy or commodity prices, I have seen rich buyers fly to this street.'

During the first Gulf war, says Abrahamson, the Saudi royal family bought 10 of the street's 66 mansions, presumably as a bolthole in case they were deposed. The Saudis still own the houses. In more recent years Russian and East European 'oligarchs', keen to expatriate their billion-dollar oil and metals fortunes, have been queuing up to buy.

Many bring with them bodyguards, bullet-proof limousines and state-of-the-art security systems . 'Over 30 years I've dealt with every nationality of buyer,' says Abrahamson. 'One gentleman from Russia never leaves The Bishops Avenue. He won't even go around the corner.'

It generally costs £3m to buy a modest five-bedroom house here - though for a certain kind of 'starter buyer' a few 1,800 sq ft flats might be available for a mere £1.5m, in a luxury apartment block currently being built.

For one of the grander mansions or villas that make this street famous, however, you'll need at least £5m, and often a lot more. The palatial Toprak Mansion - 28,000 sq ft, owned by a Turkish industrialist and known as 'Top Whack Mansion' among estate agents - is on the market for a breathtaking £50m.

Those living here can count some of the biggest names in business among their neighbours. Apart from steel tycoon Mittal (worth £14.9bn at the last count), there is property magnate Chris Lazari (£1bn), who lives a block away in the equally exclusive Winnington Road, as does Gerald Ronson (£280m). Richard Desmond (£1.9bn), press baron and owner of Express Newspapers, owns two properties on The Bishops Avenue; one, a sprawling Edwardian mansion, is being renovated by his wife Janet.

But why is living here so desirable? The houses are undeniably luxurious - all with landscaped gardens, swimming pools and spas, vast entrance lobbies and sweeping staircases - but East Finchley doesn't have the social cachet of Chelsea and Belgravia, nor the grade II-listed charms of nearby Hampstead village. Traffic thunders down the street constantly; and with all the building work going on, Rolls-Royces vie for space with white vans.

We asked Desmond. 'The building work there, funnily enough, doesn't really affect you,' he replied. 'As for neighbours - we are friendly with various neighbours and I'd rather live there than Belgravia: it's more open and green. It's near my son's school and near my mum and Janet's mum, and in the next road is my pal Gerald Ronson.

'It's like living in the country and yet only 20 minutes from the West End and 20 minutes to the City. It's also 30 minutes to Luton airport and 30 minutes to Heathrow.'

Curious for a glimpse into the private world of the very-rich, we approach a group of workmen in hard hats standing at Desmond's gateway, and ask what it's like working in such a famous tycoon's house. 'Who?' one replies with a shrug.

One capitalist's gable extension, it would seem, is much the same as any other's. But when told that their client owes much of his fortune to the success of adult magazines such as Asian Babes, they are impressed. 'Fair enough,' says one. 'Good lad.'

And that's just the thing about wealth today - people respect it, wherever it comes from. In the latest 'Rich List' of Britain's 1,000 wealthiest people, 767 are self-made men and women, while 'old money' - aristocratic and inherited wealth - is in retreat.

Not for today's millionaires the exquisitely tasteful but old and cramped townhouses of Kensington and Chelsea. They would rather buy a three-acre plot on The Bishops Avenue - and if they don't like the house that already stands there, they can always knock it down and build a new one to suit their own tastes. They've got the money to do it, and there are relatively few planning restrictions.

Attempts at quaintness or authenticity - a Georgian facade here, a whitewashed Wordsworth cottage there - are generally betrayed by sheer monstrous size: most of these structures are as big as aircraft-hangers.

On the other hand, it's difficult not to admire the sheer pluck of people who are unafraid to create their own idea of home, rather than borrow someone else's.

Driving down The Bishops Avenue has long been a favourite sport for some of London's middle classes, who enjoy sniggering at the vulgarity of the rich. They ought to be struck instead by the sheer lofty disdain with which today's billionaires defy convention.

Abrahamson says that people move to The Bishops Avenue precisely because they want to proclaim their wealth and extravagance. 'It's a significant demonstration of their status. If you live there, you don't need someone to explain to people that you're rich.'

Residents on Billionaire's Row

Owner Desmond

Est worth £1.9bn

Career The former drummer and cloakroom attendant now owns a vast publishing empire. Salary last year was £1m a week.

Owner Ronson

Est worth £280m

Career Rebuilt his Heron property empire after a spell in prison for his part in the 1980s Guinness share-trading fraud.

Owner Mittal

Est worth £14.9bn

Career Head of the world's biggest steelmaker, Mittal Steel, and recently tabled a £12.7bn offer for Arcelor, the second biggest.